External impulse launcher



June 23, 1970 J. H. JOHNSTON EXTERNAL IMPULSE LAUNCHER Filed Jan. 25', 1968 AGENT United States Patent 3,516,380 EXTERNAL IMPULSE LAUNCHER James H. Johnston, Rehoboth, Mass., assignor to the Umted States of America as represented by the Secretary of the Navy Filed Jan. 25, 1968, Ser. No. 703,227 Int. Cl. B63g /00, 9/00, 13/00 US. Cl. 114-238 8 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION This invention relates generally to systems for launching devices into a fluid environment and more particularly to a system for launching torpedoes from torpedo tubes submerged in water.

In the field of underwater torpedo launching, there are a multiplicity of launching techniques which have served their general purpose to accelerate the torpedo to full speed upon launching in order not to restrict the speed of the launching craft. However, these techniques have not proved entirely satisfactory under all conditions of service for a variety of reasons which differ with the particular technique employed. Most prior art underwater torpedo launchers have a tube penetrating into the launching craft and containing the torpedo. Such launchers rely upon a ship generated high pressure into an accumulator and an abrupt fluid discharge from the accumulator for the launch impulse with a variety of means for utilizing this impulse to impart axial launching motion to the torpedo. Perhaps the most primitive of the ejection techniques is the application of compressed air to the rear of the torpedo. This pneumatic system is highly undesirable because 1) it emits telltale bubbles to signal the fact of the torpedo launch as well as the presence of the launcher, and (2) the system degrades with increasing depth due to the greater hydrostatic pressure.

In another prior art system, compressed air drives a piston which, in turn, pushes forward a body of water forcing the torpedo out of the tube. Although this eliminates the telltale bubbles, such a system requires very large and heavy equipment, is mechanically complex, and also degrades with depth due to the back pressure of the water. Still another prior system utilizes a piston or ram catapult in which an air-actuated piston or ram mechanically engages a torpedo and forces the latter out of the tube as the piston moves within its cylinder. Such a ram catapult system has a number of disadvantages; to wit, (1) the equipment is extremely complex, (2.) the system is very heavy since the present designs require a heavy steel ram due to column buckling loads, (3) a substantially point load is applied to the torpedo, and (4) the system becomes slightly less eflicient with deeper depth once the depth has been reached at which cavitation behind the torpedo disappears. Although improvements are possible in the ram catapult systems, such as doubling the stroke length with a chain attachment to a carriage for more uniform load application, the weight cannot be significantly reduced and a heavy accumulator chamber is still required.

Yet another prior art system utilizes a turbine pump principle in which an air-driven turbine is used to power an axial water fan or impeller for ejecting the torpedo. The turbine-pump, which is now under development, offers slight improvements in weight, acceleration of the torpedo over the full length of the tube, and uniform load application. However, in its present configuration, the turbine-pump equipment is complex, and the accumulator air energy supply must discharge through the turbine back into the launching craft in order not to be effected by the back pressure at deep depths as well as to prevent telltale bubbles; this air discharge might be painful, or perhaps intolerable, to personnel on the launching craft and could require additional high volume receiver chambers. Some corrective measures for these problems in the turbine-pump system are conceivable, but the system still involves appreciable weight particularly due to the required large air accumulator. In addition to the above-mentioned individual shortcomings inherent to the particular prior art systems, there are three disadvantages common to each prior art technique. First, the fact that the launch tube penetrates the hull of the launching craft means that the exit location is adjacent the hull; the necessary result is that the torpedo launch motion is affected by the non-uniform flow of water over the craft for all locations of the launch tube except at the nose or tail of the craft. Second, the fact of penetration requires that the launch tube be designed to resist the hydrostatic pressure at any navigable depth which means that increased weight must be accepted for safety requirements. Third, each of the systems degrades with increasing depth due to (1) the greater hydrostatic pressure and resultant force which resists the forward motion of the torpedo and (2) the reduction of the driving force as the accumulators discharge and the pressure therein decreases.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is the provision of a new and improved system for launching devices into a fluid environment.

Another object is to provide a new and improved system for launching torpedoes from submerged torpedo tubes.

A further object of the invention is the provision of a system for launching torpedoes from submerged torpedo tubes which is simple, small and lightweight.

Still another object is to provide a submerged torpedo launching system which does not require a discrete high pressure fluid accumulator.

Yet another object of the present invention is the provision of a submerged torpedo launching system which virtually eliminates substantially all of the telltale bubbles ordinarily emitted by many prior art systems.

A still further object is to provide a submerged torpedo launching system which does not degrade with increasing depth but, in fact, operates with even greater efficieney at increased depths.

Yet a still further object of the present invention is the provision of a submerged torpedo launching system in which the driving force is substantially uniformly applied to the torpedo.

But a still further object is to provide a submerged torpedo launching system in which the torpedo tube need not penetrate the hull of the launching craft.

One other object of the present invention is the provision of a submerged torpedo launching system in which the launching tube need not be designed to resist the hydrostatic pressure at the depths of its environment.

One still further object is to provide an external impulse weapons launching system utilizing for the driving force the ambient pressure in a fluid environment.

Briefly, in accordance with one embodiment of this invention, these and other objects are attained by utilizing the ambient fluid environment as the accumulator with an abrupt discharge into an evacuated fluid receiver tank of a suflicient volume to perform the required work. Since the driving fluid in such a system has no significant pressure-volume relationships due to the theoretically infinite pressure source, the fluid receiver tank volume may be considerably smaller than that required by a conventional accumulator, and there is no decrease in driving pressure until the fluid receiver tank is full as there is with a conventional pressurized accumulator. Such a system may be achieved by providing, in a torpedo tube having a restricted muzzle area, means for utilizing the ambient seawater pressure to eject a torpedo by discharging the water in front of a piston carriage into an empty fluid receiver tank so that the differential pressure on the two faces of the piston carriage will produce a sufficient net drive force to eject the torpedo.

BRIEF DESCRIPTION OF THE DRAWINGS A more complete appreciation of the invention and many of the attendant advantages thereof will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein there is illustrated a diagrammatic side elevation, partly in section, of a preferred embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing, the external impulse weapons launcher of the present invention is shown as consisting essentially of an open-ended generally cylindrical torpedo tube 2 having a restricted opening 4 at the fore end thereof so as to form a reduced muzzle area and a substantially unrestricted opening 6 at the aft end. A torpedo 8 is coaxially positioned within torpedo tube 2 and extends through the restricted fore opening 4 thereof. It should be noted that the outside diameter of torpedo 8 closely approximates the diameter of restricted fore opening 4 in the torpedo tube, but that the outside diameter of the torpedo is significantly smaller than the inside diameter of the torpedo tube so as to form an annular chamber 10 therebetween. Slideably positioned within tube 2 is an annular piston carriage 12 having an outside diameter closely approximating the inside diameter of torpedo tube 2 which engages the rearward end of torpedo 8. A fluid receiver tank 14 is connected, via a dump valve 16, and an opening in the wall of tube 2 to annular chamber 10 near the fore end thereof by appropriate conduits. Torpedo 8 preferably should be restrained in place prior to launching by a conventional means such as a restraining wire 18 attached to the torpedo and torpedo tube which prevents forward movement and a stop member 20 attached to the torpedo tube by conventional means (not shown) which bears against piston carriage 12 to prevent rearward movement thereof. In accordance with one embodiment of this invention, a fluid seal, such as O-rings 22, may be provided between the torpedo and torpedo tube and between the piston carriage and the torpedo tube, if there is an inlet valve 24 connected by appropriate conduits to annular chamber 10.

In operation, torpedo 8 is inserted in torpedo tube 2 with the fore end of the torpedo extending through the torpedo tube muzzle defined by restricted fore opening 4 therein. Piston carriage 12 is then inserted into torpedo tube 2 and bears against the aft end of the torpedo. Stop member 20 is then attached to the torpedo tube, and restraining wire 18 is inserted through an opening in the torpedo. The torpedo is drawn back by the restraining wire so that piston carriage 12 is tightly restrained between stop member 20 and torpedo 8, and finally the restraining wire is secured to the torpedo tube. Dump valve 16 is initially closed and fluid receiver tank 14 is evacuated by conventional means (not shown). Inlet valve 24 is initially open and the external impulse weapons launcher of the present invention is submerged causing water to fill annular chamber 10 so that hydrostatic pressure is applied to the torpedo tube uniformly inside and out thereby eliminating all hydrostatic pressure stresses. When it is desired to launch the torpedo, inlet valve 24 and dump valve 16 are simultaneously actuated by conventional means (not shown) to assume closed and opened conditions, respectively, whereupon the water in annular chamber 10 discharges into fluid receiver tank 14. The net force then acting on the torpedo is equal to the area of unrestricted aft opening 6 minus the area of restricted fore opening 4 multiplied by the ambient seawater pressure. This force is suflicient to break restraining wire 18 driving the piston carriage 12 and torpedo 8 down the tube until the torpedo is ejected. In the preferred embodiment disclosed herein, the forward motion of piston carriage 12 is stopped when it abuts that forward portion of torpedo tube 2 which defines restricted fore opening 4 although it is contemplated that other conventional stop means might be employed.

Obviously numerous modifications and variations of the present invention are possible in the light of the above teachings. The foregoing description is intended to be illustrative of only the preferred embodiment which is, in some respects, more specific and sophisticated than is necessary to practice the invention in accordance with the teachings herein disclosed. For example, the disclosed system may be advantageously utilized with the omission of inlet valve 24 as wellas the sealing means illustrative as O-rings 22. In such a case annular chamber 10 is initially filled by leakage between the torpedo and the torpedo tube and between the piston carriage and the torpedo tube. In this instance, the net force driving the torpedo forward upon opening valve 16 is the area of the unrestricted aft opening minus the area of the restricted fore opening times the ambient seawater pressure less leakage. Furthermore, the restriction shown herein as restricted fore opening 4 need not be physically positioned at the end of the torpedo tube but may, in fact, be positioned at practically any point so long as the fluid receiver tank is connected to annular chamber 10 behind the restriction; however, by placing the restriction at the forward extremity, the volume of annular chamber 10 and the stroke of piston carriage 12 may be maximized. It is also quite obviously recognized that the restriction may be formed'by a separate member attached to the torpedo tube instead of one integral therewith. In addition, the cross-sectional shapes of the torpedo, torpedo tube and chamber 10 are not limited to circular, circular and annular, respectively, since the torpedo need not be cylindrical, and the torpedo tube may be any conduit. The use of fluid receiver tank 14 and dump valve 16 have been illustrated as the preferred devices for evacuating chamber 10, but other conventional means, such as a vacuum pump, may be used instead. Although piston carriage 12 has been shown as annular and as having an aperture therein, that member may be a completely c osed piston.

It should also be recognized that fluid receiver tank 14 need not be initially evacuated so long as it is evacuated prior to the opening of dump valve 16. Moreover, it is within the contemplation of the present invention that piston carriage 12 may be eliminated in which case the force on the torpedo is achieved by fluid drag over the torpedo body. In this instance, the fluid receiver tank size would have to be significantly larger to accommodate the larger flow rates over the same time period for the same thrust as compared with the flow rates required with the piston carriage. This c ncept also may be applied to ram catapult systems to power the pistons thereof or to turbine-pump systems to power the turbines thereof; however, the additional mechanisms appear to be unnecessarily redundant. It should be furthermore recognized that the external impulse weapons launcher of the present invention becomes more eflective with increased ambient seawater pressures at greater depths, and indeed, perhaps too eifective without some throttling of dump valve 16 or stroke limitation on piston carriage 12. Although the external impulse weapons launcher of the present invention has been described in terms of an underwater torpedo launcher, it is within the contemplation of this invention that the disclosed techniques may be used to drive launchers of any description which employ a fluid for transmitting the motive power provided the ambient pres sure of the environmental fluid is suflicient to produce the desired net driving force. Such a system may be used for other underwater purposes, such as embedment anchor ejection means, submarine signal launching means, ejection means for various underwater swimmer Weapons and harpoons and others. This invention may also be practiced in a gaseous environment for a variety of purposes and should not be considered as limited to water or liquid environmental applications. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.

What is claimed as new and secured by Letters Patent of the United States is:

LApparatus for launching a device in a fluid environment comprising:

means providing an interior channel wherein the device is positioned and having a first extremity and a second extremity, said second extremity being of a cross-sectional area less than the cross-sectional area of said first extremity; said second extremity having an opening therein of a cross-sectional area and shape suitable for receiving in fluid tight relationship one end of said device;

said first extremity being configured to matingly engage the opposite end of said device in sealing relationship therewith and movable with said device in the direction of said second extremity; and

means for evacuating said channel when a device is disposed therein in sealing relationship therewith.

2. The apparatus of claim 1 wherein said first extremity comprises a piston carriage means slideably positioned within said channel.

3. The apparatus of claim 1 wherein said means for evacuating said channel comprises a fluid receiver tank.

4. Apparatus for launching an elongate, generally cylindrical body in a fluid environment comprising:

an elongate tube providing a generally cylindrical passageway having over a major portion thereof a crosssectional area larger than the body and a cross-sectional shape sutficient to accommodate the body;

one extremity of said major portion of said passageway having a reduced opening for constricting the cross-sectional area and shape of said major portion of said passageway to substantially the same crosssectional area and shape of the body;

generally cylindrical piston carriage means slidably disposed within said tube in said major portion of said passageway, one surface thereof being directly open to said fluid environment; and

means operative when a body is disposed in said tube for evacuating said major portion of said passageway.

5. The apparatus of claim 4 further comprising:

means for eflecting a dynamic fluid seal between said tube and a body at the one extremity of said tube when said body is disposed therein prior to launching; and

means for selectively providing fluid from said environment to said passageway.

6. The apparatus of claim 4 wherein said means for evacuating said major portion of said passageway comprises a fluid receiver tank which is adapted to be evacuated.

7. The apparatus of claim 6 wherein said fluid receiver tank is fluidly connected to said major portion of said passageway near said reduced opening.

8. The apparatus of claim 7 further comprising:

a selectively actuable valve interposed between said major portion of said passageway and said fluid receiver tank for selectively regulating the fluid flow therebetween.

References Cited UNITED STATES PATENTS 765,305 7/1904 Brady 114-238 1,526,256 2/1925 Techel 114238 2,837,971 6/1958 Wosak 89-5 BENJAMIN A. BORCHELT, Primary Examiner T. H. WEBB, Assistant Examiner US. Cl. X.R. 89-5 

